

498 PROCEEDINGS OF SCIENTIFIC SOCIETIES. 
Northward from Lac Travers commences a vast lake basin extending 
continuously to the north end of Lake Winnipeg, including this lake, Lake 
Winnipigoos and Lake Manitoba. The greater part of this ancient lake- 
bed is now dry, leaving a well-defined beach to mark its former extent. 
Although the Red river of the north flows north along the lowest line of 
this bed, he concluded that the waters of this basin once flowed south- 
ward, through the Minnesota river, into the Mississippi 
The present level of Lake Winnipeg aegis to Mi Hines, is six 
To 
good description of this outlet, as it is never used for a line of a 
cation; it abounds in rapids and falls, which seem to show its rece 
igi If we suppose the ice of the glacial period to have ee this, it 
rel have given the lake the whole extent of the basin, and caused its 
ee southward; but this-will not account for all the phenomena 
observed. 
pai more mapon mpeni of a change of outlet froma southern 
to a northern one, is to attribute it to a northern depression of the basin; 
for it is found ia Fakti dio kari formerly. had a southern outlet through 
the Illinois river, and Lake Winnebago also had a much greater extent 
and a southern outlet. The shores of all the lakes show the water to be 
receding from their southern ends and encroaching upon the n northern. 
This northern depression is known to be going on along the Atlantic 
coast from New Jers rsey to Greenla na 
n. 
waters of Winnipeg basin, even if they had continued to flow southward 
could not have excavated the passage-way now occupied by the Minnesota 
and Mississippi rivers, and that we must go farther back in time to reac cha 
sufficient cause. In doing this we must first consider the character of the 
rivers which PETEN in pEr region previous to the glacial epoch. urin, 
the Cretaceous period we know that an ocean extended from the present 
Gulf of Mexico to the Arctic Ocean, covering a large portion of the space 
between the Missouri and Rocky Mountains. At that time eg pa 
country through which the Mississippi now flows was dry la Jan a 
slopes must have sent its waters westward to the Cretaceous pe 
the continent rose this Cretaceous ocean manages pene and the poe 
period began with great fresh-water lakes along the base ye the Rocky 
Mountains; into these lakes the waters of the Upper Miss 
continued apparently to the time preceding the glacial “hoa 
vation at the south-west seems to have been in progress 



